Actuator for a micro-electromechanical valve assembly

• US 7,140,719 B2
• Filed: 07/06/2004
• Issued: 11/28/2006
• Est. Priority Date: 07/15/1997
• Status: Expired due to Fees

• Current Assignee: Zamtec Limited (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia
• Primary Examiner(s): Do, An H.
• Application Number:
  US10/884,887
• Publication Number:
  US 20050036001A1
• Time in Patent Office: 875 Days
• Field of Search: 347/54, 347/56, 347/65
• US Class Current: 347/54
• CPC Class Codes: B41J 2/14427 Structure of ink jet print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/1623 bonding and adhesion
• CPC Class Codes: B41J 2/1626 etching
• CPC Class Codes: B41J 2/1628 dry etching
• CPC Class Codes: B41J 2/1629 wet etching
• CPC Class Codes: B41J 2/1631 photolithography
• CPC Class Codes: B41J 2/1632 machining
• CPC Class Codes: B41J 2/1635 dividing the wafer into individual chips
• CPC Class Codes: B41J 2/1637 molding
• CPC Class Codes: B41J 2/1639 sacrificial molding
• CPC Class Codes: B41J 2/1642 thin film formation by CVD [chemical vapor deposition]
• CPC Class Codes: B41J 2/1643 thin film formation by plating
• CPC Class Codes: B41J 2/1645 thin film formation by spincoating
• CPC Class Codes: B41J 2/1646 thin film formation by sputtering
• CPC Class Codes: B41J 2/1648 Production of print heads with thermal bend detached actuators
• CPC Class Codes: B41J 2/16585 for paper-width or non-reciprocating print heads
• CPC Class Codes: B41J 2/17503 Ink cartridges
• CPC Class Codes: B41J 2/17513 Inner structure
• CPC Class Codes: B41J 2/17596 Ink pumps, ink valves
• CPC Class Codes: B41J 2002/041 Electromagnetic transducer
• CPC Class Codes: B41J 2202/21 : Line printing
• CPC Class Codes: B82Y 30/00 : Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: G06F 21/79 : in semiconductor storage media, e.g. directly-addressable memories
• CPC Class Codes: G06F 21/86 : Secure or tamper-resistant housings
• CPC Class Codes: G06F 2221/2129 : Authenticate client device independently of the user
• CPC Class Codes: G06K 1/121 : by printing code marks applying code marks to labels B65C9/46; marking or coding completed packages B65B61/26
• CPC Class Codes: G06K 19/06037 : multi-dimensional coding
• CPC Class Codes: G06K 7/14 : using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1417 : 2D bar codes
• CPC Class Codes: G11C 11/56 : using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
• CPC Class Codes: H04N 1/2112 : using still video cameras
• CPC Class Codes: H04N 1/2154 : the still video camera incorporating a hardcopy reproducing device, e.g. a printer
• CPC Class Codes: H04N 2101/00 : Still video cameras
• CPC Class Codes: H04N 23/00 : Cameras or camera modules comprising electronic image sensors; Control thereof
• CPC Class Codes: H04N 5/2628 : Alteration of picture size, shape, position or orientation, e.g. zooming, rotation, rolling, perspective, translation
• CPC Class Codes: H04N 5/7458 : the modulator being an array of deformable mirrors, e.g. digital micromirror device [DMD]

Abstract

An elongate actuator is anchored at one end to the wafer substrate to be in electrical contact with the drive circuitry layers. A closure member is mounted on an opposite end of the elongate actuator. The actuator is configured to receive an electrical signal from the drive circuitry layer to displace the closure member between a closed position in which the closure member covers the fluid supply opening and ink is inhibited from flowing through the fluid supply channel and an open position. The elongate actuator is shaped so that, in a rest condition, the actuator encloses an arc. The actuator includes a heating portion that is capable of being heated on receipt of the electrical signal to expand. The heating portion is configured so that, when the portion is heated, the resultant expansion of the portion causes the actuator to straighten at least partially and a subsequent cooling of the portion causes the actuator to return to its rest condition thereby displacing the closure between the closed and open positions.

Claims

1. An elongate actuator for moving a closure member in a micro-electromechanical valve assembly for controlling a flow of fluid through a fluid supply channel, the channel being defined by a wafer substrate and drive circuitry layers positioned on the wafer substrate and terminating at a fluid supply opening, the actuator having a first end anchored to the wafer substrate so as to be in electrical contact with al least one of the drive circuitry layers and a second end connected to the closure member so as to move it between a closed position, in which the closure member covers the fluid supply opening and ink is inhibited from flowing through the fluid supply channel, and an open position, in which the fluid supply opening is opened to allow the ink to flow through the fluid supply channel, wherein

at least a portion of the actuator, in a rest condition, has an arcuate shape and is configured to be heated, upon receiving an electrical current from the drive circuitry, such that when the portion is heated it expands and causes the actuator to straighten sufficiently to displace the closure member from closed to an open position;

and a subsequent cooling of the portion, after the current is discontinued, causes the actuator to return to its rest condition returning the closure to the closed position.

2. An elongate actuator as claimed in claim 1, the actuator including a body portion that is of a resiliently flexible material having a coefficient of thermal expansion which is such that the material can expand to perform work when heated, the heating portion being positioned in the body portion and defining a heating circuit of a suitable metal.

3. An elongate actuator as claimed in claim 2, in which the heating circuit includes a heater and a return trace, the heater being positioned proximate an inside edge of the body portion and the return trace being positioned outwardly of the heater, so that an inside region of the body portion is heated to a relatively greater extent with the result that the inside region expands to a greater extent than a remainder of the body portion.

4. An elongate actuator as claimed in claim 3, in which a serpentine length of said suitable material defines the heater.

5. An elongate actuator as claimed in claim 3, in which the body portion is of polytetrafluoroethylene and the heating circuit is of copper.

6. An elongate actuator as claimed in claim 1, the actuator defining a coil that partially uncoils when the heating portion expands.